A five-year data analysis project is designed to yield a comprehensive understanding of the developmental interplay between genetic and social factors in the trajectory of mood and behavioral disorders from early adolescence into young adulthood. The study will use longitudinal data from the Virginia Twin Study of Adolescent Behavioral Development (8-16 yr) and its Young Adult Follow-Up (20+ yr). The data comprise intensive, juvenile and young adult longitudinal, multi-rater (child, parent, teacher), interview and questionnaire assessments of psychopathology, environment and psycho-social risk factors in 1412 families of like- and unlike-sex adolescent twin pairs and their parents. Outcomes assessed in twins and their parents include symptoms, severity, impairment and treatment relating to: anxiety disorders (AD); depression (MD); conduct disorder (CD); oppositional-defiant disorder (ODD); attention-deficit hyperactivity disorder (ADHD); Substance use disorders (SUD). Potential covariates and risk factors include: parental psychopathology; pre- and peri-natal factors; life-events; home environment; socioeconomic and contextual variables; personality; interactions with peers, siblings and parents. The project will: 1) characterize the impact of age and sex on the contributions of genes, family environment and individual environment on principal mood and behavioral disorders and risk factors through adolescence into young adulthood.; 2) identify specific family and individual environmental variables that contribute to overall estimates of environmental components of variance; 3) analyze the interplay of genes and environment on development of mood and behavioral disorders, including the interaction (GxE) and correlation (rGE) of genotype with the impact of specific environmental factors at different stages of life history; 4) resolve heterogeneity in adolescent and young adult psychopathology expressed in differential patterns of genetic and environmental etiology, comorbidity, developmental trajectory, symptom pattern, severity, impairment and environmental risk; 5) establish the profile of early genetic and environmental risk factors and behaviors that best predict young adult psychopatholgy; 6) quantify the roles of parental psychopathology, family cohesion and communication that affect the consistency of assessments derived from parents, teachers and children and determine the combination of multiple ratings that best predict juvenile impairment and longer-term psychiatric outcomes in young adulthood. Where appropriate, the robustness of findings will be explored to minimize misleading claims and new analytical methods employed to reflect the new generation of questions.